i can not find out what i am supposed to do! i am at the part where u r underwater and those giant fishy eels r swimming around! and u have to like go to an air filter so u can get air while underwater. HELP! please

i can not find out what i am supposed to do! i am at the part where u r underwater and those giant fishy eels r swimming around! and u have to like go to an air filter so u can get air while underwater. HELP! please

well u have to find the key to open a door its in one of the holes on the bottom i dont remember which one though i hope that helps u